This invention relates to entropy-based quantization, including maximum-entropy quantization, and more particularly to use of such quantization to communicate link state in a communication network, and yet more particularly to communication of link state for the purpose of relay-based communication in the network.
In a wireless mobile network, relaying is a viable technique for maintaining high performance communication among different parties. As an example, in a heterogeneous network two users may communicate via an intermediate node rather than or in addition to communicating directly to improve transmission rate and coverage. In an ad hoc setting, relaying can be applied among all users [Dressler et al., 2014]. A third user can act as a relay for two active users, such as in emergency message dissemination [Bi et al., 2010]. Relaying can also be applied in other scenarios such as infrastructure-aided, cellular, and vehicular networks. By employing two-way relaying, both the rate and reliability can be increased [Haija and Vu, 2015] [Pinals and Vu, 2014].
One approach to relaying uses a decode-and-forward (DF) strategy. With DF, the effects of the noise are removed completely at the relay by decoding the message before re-encoding it to transmit to the destination [Cover and El Gamal, 1979]. The composite DF transmission technique (e.g., as developed in [Pinals and Vu, 2014]) combines two transmission techniques such that the resulting scheme can be tailored to the link state of the system in order to achieve the best rate using minimum relay transmit power.
The state of a link in a radio network may be affected by Rayleigh fading. Given that links between users fade randomly, the transmission scheme preferably is adapted to the link state in order to obtain the best rate performance. To employ the composite relaying scheme in fading, the link states are distributed among the nodes, and by necessity must be quantized for transmission. Conventional quantization approaches, which have been a well studied topic in data compression [Max, 1960], [Lloyd, 1982] and have been applied in communication, may be applied to the communication of link state via codebook design for limited feedback [Love et al., 2008]. Conventionally, scalar quantizers are designed to be optimal in the sense that they minimize the expected distortion, such as the Lloyd-Max algorithm [Max, 1960] [Lloyd, 1982].